Retractor

ABSTRACT

A retractor for running pipe into and out of a hole is provided with a fluid operating system for opening and closing the several grippers, in which the grippers are opened and closed by pressure responsive members which are subjected to a high- and lowpressure fluid system through a suitable three-way valve to effect opening, closing, and gripping with a minimum volume of high-pressure fluid being utilized.

United States Patent 7 Appl. No.

Dale 1!. Pryor Houston, Tex.

Mar. 9, 1970 Oct. 5, 1971 Youngstown Sheet and Tube Company Youngstown, Ohio Inventor Filed Patented Assignee RETRACT OR 5 Claims, 4 Drawing Figs.

Int. Cl B65h 17/34 Field of Search 226/173;

'[56] References Cited UNITED STATES PATENTS 3,330,459 7/1962 Cullen et a1 226/173 3,191,522 6/1965 Drake et a1. 226/173 X Primary Examiner-Allen N. Knowles Assistant Examiner-Gene A. Church Attorneys-J. Vincent Martin, Joe E. Edwards, M. H. Gay,

Alfred H. Evans and Jack R. Springgate M b O o 1 U o a 00 0 RETRACTOR This invention relates to retractor apparatus for handling flexible pipe and more particularly to an improved fluid system for opening and closing the grippers of such apparatus. In Cullen U.S. Pat. Nos. 2,892,535 and 3,330,459, a retractor apparatus is shown for handling flexible pipe. These apparatus utilize high-pressure fluid for operating the grippers. As this invention is an improvement on the Cullen Patents only the fluid system will be disclosed in detail, and reference is made to the Cullen Patents for a complete disclosure of the overall apparatus and its method of operation.

An object of this invention is to provide a retractor apparatus of the type disclosed in the Cullen Patents in which the volume of high-pressure fluid needed to operate the gripper system is substantially reduced.

Another object is to provide a fluid system for a retractor apparatus in which fluid forced from one gripper during the opening of the gripper is utilized to close another gripper on the chain.

Still another object is to provide a retractor apparatus fluid system, as in the preceding object, in which the timing of the opening and closing of grippers is not critical and fluid exhausted from a gripper during opening may be accumulated and utilized to close another gripper.

Other objects, features and advantages of the invention will be apparent from the drawings, the specification, and the claims.

In the drawings wherein an illustrative embodiment of this invention is shown;

FIG. I is a view in side elevation of a retractor apparatus constructed in accordance with this invention;

FIG. 2 is a view in front elevation of a section of the gripper chain;

FIG. 3 is a schematic view showing the hydraulic circuit in two pairs of opposed pistons for closing opposed grippers;

FIG. 4 is a flow diagram illustrating the fluid system of this invention.

Referring first to FIG. I, a base, indicated generally at 10, may be supported on a suitable substructure (not shown) over the site of the well to be drilled. The base supports m mast, one side of which is indicated generally at 13. A comparable side (not shown) is spaced from the side 13, and suitable pairs of sprockets, one of which is indicated generally at 14, are provided at the upper and lower ends of the mast. The endless chain indicated generally at is trained over four such sprockets, two at the upper and two at the lower end of the mast in the manner taught in the Cullen Patents.

Alternate chain links 16 are carried on a pair of trunnions I7 and 18 on a gripper assembly.

Each gripper assembly may include one or more sets of opposed grippers. Preferably, two sets of opposed grippers are carried on each assembly as shown in FIG. 2 wherein grippers 19, 20, 21 and 22 make up one assembly and receive fluid from a common control valve. As shown in FIG. 3, each gripper assembly is controlled by a single three-position valve, indicated generally at 23, so that pressure acting on each gripper is the same for each assembly.

Thus, in the assembly shown in FIG. 3, fluid from the threeposition valve 23 passes through conduit 24 into the back of cylinders 25 and 26 and through the connecting lines 27 and 28 into the back of cylinders 29 and 30. Fluid from the threeposition valve 23 passes through the conduit 31 into the front of cylinders 25 and 26 and through lines 32 and 33 into the front of cylinders 29 and 30. Thus, substantially equal pressure is effective in the opposite ends of each of the fluid cylinders 25, 26, 29, and 30.

Reference is now made to FIG. 4 wherein the operation of the grippers in accordance with this invention is illustrated. It will be understood that the opening and closing functions take place adjacent the sprockets, while the gripping function takes place during the passage of a gripper assembly vertically between spaced sprockets on the front side of the rig. While fluid is directed to only one cylinder in the schematic of FIG. 4, such fluid will actually be directed to all four cylinders as shown in FIG. 3.

As shown in FIG. 4, each gripper 34 is connected to a pressure responsive member or piston 35 by a suitable connecting rod 36. Preferably, this connecting rod is relatively large in diameter so that there is a substantial difference in the pressure responsive surface or area on the rod side and on the other side of the piston 35. Fluid is directed to and from the cylinder 37, in which the piston 35 reciprocates through suitable conduits 38 and 39 from the three-position valve indicated generally at 23.

The fluid circuit for operating the grippers includes a highpressure side and a low-pressure side. The high-pressure side includes a manifold line, indicated generally at 41, which is preferably a continuous or closed line. Connected to the line through a suitable swivel 42 is a tank 43 or source of fluid, preferably liquid, which is supplied to the high-pressure manifold 41 by a pump 44. Preferably, the pump will maintain a selected pressure within the manifold line 41 at all times.

Branch lines 45 connect the high-pressure manifold 41 with the three-position valves 23 through suitable check valves 46. These check valves prevent backflow of fluid in the event of a failure in the system, a shutdown of the pump or the like, so that the system is failsafe and the grippers will be maintained in gripping relationship with the pipe until the three-position valve is shifted to release the gripping action.

The fluid circuit also includes a low-pressure side, that is a selected lower than the pressure in the high-pressure side. This low-pressure pressure is maintained in a suitable closed manifold conduit 47 which is connected through branches 48 to the three-position valves 23. The fluid from the low-pressure circuit is returned to tank 43 through the swivel 49.

The selected lower pressure is maintained in the low-pressure side of the circuit by the back pressure valve indicated generally at 51. This back pressure valve maintains the desired lower pressure and permits excess fluid to pass into the tank 43 through the outlet line 52.

Preferably, an accumulator 53 is provided in the circuit upstream of the back pressure valve. This accumulator will accumulate fluid from the opening of one gripper assembly and use such accumulated fluid to close another gripper assembly without the necessity of having one gripper assembly open at exactly the same time that another gripper assembly closes.

The three-position valve 23 has one position in which the piston moves the gripper toward closed position. In this position the low-pressure side of the circuit is connected to both sides of the piston 35. As the connecting rod 36 effectively reduces the pressure responsive area of the piston on the rod side, the gripper is moved toward closed position. The lowermost valve 23 is shown in this relationship with the inlet conduit 45 blocked off and the l0w-pressure branch conduit 48 connected to both lines 38 and 39.

The three-position valve means also has a second position which connects the low-pressure side through lines 48 and 38 to the rod side of the piston 35. The high-pressure side of the circuit, connected through lines 45 and 39 to the other side of the piston, urges the gripper toward closed position under high pressure. This is the gripping relationship and is shown in the middle of the flgure.

At the top of the figure there is shown the third position of the three-position valve means, in which the rod side of the piston is connected to the high-pressure side through lines 38 and 45. The other side of the piston is connected to the lowpressure side of the circuit by connecting lines 39 and 48. This moves the gripper toward open position.

It will be apparent that the relative effective areas of the piston and the differential in pressure should be correlated so that the force exerted by the high-pressure fluid on the small area of the rod side of the piston is sufficient to overcome the lower pressure on the larger area on the other side of the piston and move the piston to open position.

There are a number of the gripping assemblies on the endless chain. They are constantly opening and closing. If they were timed to open and close at exactly the same instant, the fluid from the opening assembly could be used to close a closing assembly. By providing the accumulator 53, it is not necessary that the opening and closing of two assemblies be exactly timed as the fluid pressure will be maintained in the accumulator 53 to close the assemblies as the valve is shifted to closing position.

As the fluid from an opening gripper is utilized to close another gripper under low pressure, very little additional fluid need be introduced into the system to close each gripper. Once closed the gripper cylinder is subjected to high-pressure fluid, but as hydraulic fluid will be utilized, only a slight amount of additional fluid will be introduced in the cylinder 37 to grip the pipe. During the opening of the gripper, a small amount of high-pressure fluid is utilized, but as the connecting rod is relatively large in size the amount of fluid necessary for this purpose is kept at a minimum. By transferring low-pressure fluid from the opening cycle to the closing cycle, the small amount of additional high-pressure fluid introduced during gripping and opening is sufficient to maintain the fluid flow to the low-pressure side. Thus, it will be seen that the amount of high-pressure fluid flow necessary to operate the grippers has been substantially reduced by this invention, and it is not necessary to design the system to handle large volumes of high-pressure fluid.

The valves 23 are shown schematically. Any type valve may be used. Preferably, they are rotary valves which minimize leakage problems.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

l. A retractor comprising,

a support,

an endless chain on the support,

a plurality of grippers carried by the chain,

a plurality of pressure responsive members having opposed pressure responsive surfaces,

connecting rods connecting said pressure responsive members to said grippers for opening and closing the grippers,

said pressure responsive members having a lesser efi'ective area on the rod side,

a fluid circuit having a high-pressure side and a low-pressure side,

means for maintaining a selected high pressure in said highpressure side of the circuit,

means for maintaining a selected low pressure in the lowpressure side of the circuit, and three-position valve means connected to the opposite sides of each pressure responsive member and to the highand low-pressure sides of said fluid circuit, said valve means in one position connecting the low-pressure side of the circuit to both sides of the pressure responsive member to move the gripper toward closing position under low pressures, said valve means in a second position connecting the lowpressure side of the circuit to the rod side of the pressure responsive member and the high-pressure side of the circuit to the other side of the pressure responsive member to urge the gripper toward closed position under high pressures, said valve means in a third position connecting the rod side of the pressure responsive member to the high-pressure side of the circuit and the other side of the pressure responsive member to the low-pressure side of the circuit to move the gripper toward open position. 2. The retractor of claim 1 wherein the pressure responsive members are provided by pistons.

3. The retractor of claim 1 wherein the means for maintaining high pressure is a pump and the means for maintaining the selected low pressure is a back pressure valve.

4. The retractor of claim 1 wherein an accumulator is provided in the low-pressure side of the fluid circuit.

5. The retractor of claim 1 wherein the pressure responsive members are provided by pistons,

the means for maintaining a selected high pressure is a pump,

the means for maintaining a selected low pressure is a back pressure valve and an accumulator is provided in the lowpressure side of the fluid circuit. 

1. A retractor comprising, a support, an endless chain on the support, a plurality of grippers carried by the chain, a plurality of pressure responsive members having opposed pressure responsive surfaces, connecting rods connecting said pressure responsive members to said grippers for opening and closing the grippers, said pressure responsive members having a lesser effective area on the rod side, a fluid circuit having a high-pressure side and a low-pressure side, means for maintaining a selected high pressure in said highpressure side of the circuit, means for maintaining a selected low pressure in the lowpressure side of the circuit, and three-position valve means connected to the opposite sides of each pressure responsive Member and to the high- and lowpressure sides of said fluid circuit, said valve means in one position connecting the low-pressure side of the circuit to both sides of the pressure responsive member to move the gripper toward closing position under low pressures, said valve means in a second position connecting the lowpressure side of the circuit to the rod side of the pressure responsive member and the high-pressure side of the circuit to the other side of the pressure responsive member to urge the gripper toward closed position under high pressures, said valve means in a third position connecting the rod side of the pressure responsive member to the high-pressure side of the circuit and the other side of the pressure responsive member to the low-pressure side of the circuit to move the gripper toward open position.
 2. The retractor of claim 1 wherein the pressure responsive members are provided by pistons.
 3. The retractor of claim 1 wherein the means for maintaining high pressure is a pump and the means for maintaining the selected low pressure is a back pressure valve.
 4. The retractor of claim 1 wherein an accumulator is provided in the low-pressure side of the fluid circuit.
 5. The retractor of claim 1 wherein the pressure responsive members are provided by pistons, the means for maintaining a selected high pressure is a pump, the means for maintaining a selected low pressure is a back pressure valve and an accumulator is provided in the low-pressure side of the fluid circuit. 